DocScrutinizer: (pin names) there are the confusing differences between the component we use and all the others. e.g., 1) parallel transformers followed by antiparallel ones vs. antip. followed by parallel. 2) that the pin numbering suggests that TX and RX are swapped, along with the +/- polarity. not sure if the latter is a real difference or if they just got it wrong in the data sheet

the AP vs. P. issue is trickier: some have P-AP on TX and RX. some have P-AP on one and AP-P on the other. now is this equivalent ? if yes, why would even the same company sometimes have both variants ?

DocScrutinizer: heh :) that's basically the answer i'm after. one of 1) it may be different, but irrelevant in practice. 2) it's something we can worry about later, when we're really bored some day. 3) what we have a is a very crippled ethernet that performs way below specification.